This application is in response to NIMH Program Announcements to encourage innovative analysis of existing data sets to "elucidate risk factors and processes for the development of mental health problems in order to guide the development of prevention and early intervention strategies." The application focuses on posttraumatic stress disorder (PTSD), which continues to be a pressing public health challenge, not only among military personnel, but also among community residents who are victims of domestic violence, rape, physical assault, terrorist attacks and other severely traumatic events. The prevalence of traumatic events as defined in DSM-IV in US communities is estimated at 75-85%. Roughly 10% of adults exposed to trauma develop PTSD and an additional 25%, partial PTSD. Previous studies have identified suspected causal determinants that might account for PTSD, when it occurs. The proposed research capitalizes upon prospectively gathered data, beginning in childhood and continuing to early adulthood, to shed more definitive light on issues previously addressed only cross-sectionally and retrospectively. The research plan builds from an NIMH/NIDA-sponsored prevention research program at Johns Hopkins University (JHU), which involved primary school students as they entered urban (primarily inner city) firstgrade of Baltimore City Public Schools in 1985 and 1986 (n=2311) and assessed repeatedly since then, most recently as young adults, when they completed interviews that included assessment of traumatic events and PTSD (n=1698; 74.5% of the surviving cohort). Epidemiological and biostatistical approaches to longitudinal data and repeated assessments will be used to probe the observed associations for possible causal significance. This will include longitudinal regression models, in which latent classes of children, characterized by trajectories of psychiatric and behavioral disturbances, are evaluated as mediators leading toward exposure to trauma and PTSD or related syndromes. Effect-buffering characteristics of individuals or setting that might shield young people from exposure to trauma or buffer PTSD responses to these exposures will be identified. The effects of interventions to enhance academic mastery and pro-social behavior, conducted in this cohort in early school years, on exposure to trauma and PTSD will be evaluated.